Embodiments relate to a light emitting diode (LED) and/or a LED driving circuit. White LEDs may be used for illumination (e.g. a backlight unit of a mobile communication device). When applying LEDs to mobile communication devices, it may be desirable for LEDs to have relatively low power consumption in order for them to be used for a relatively long period of time. It may be desirable for a LED driving circuit to maintain a consistent level of light emitted from LEDs.
The amount of light emitted from an LED may be determined as a function of current and temperature supplied to the LED, irrespective of an emitting color. The brightness of a LED may be non-linearly reduce during operation. For example, the brightness of a white LED may be decrease after a prescribed time elapses. Even though the same current may flow into a LED, the brightness of the LED may change due to changes in ambient temperature of the LED during operation.
LEDs mounted in a backlight unit may have a serial and/or parallel structure. When the LEDs are simultaneously driven, the amount of light from the LEDs should be maintained relatively constant by supplying the same current to each of the LEDs.
An example LED driving circuit for driving a white LED may utilize a charge pump. A LED driving circuit may sense the amount of voltage applied to the LED and/or a voltage across both ends of the LED and control the amount of voltage applied to the LED using the sensed voltage. However, such an LED driving circuit may having limitations in keeping the amount of light emitted from the LED reasonably constant.
A LED driving circuit may receive light emitted from an LED and controlling the driving of the LED by using a received result (e.g. sensed light) as feedback. A light sensing LED driving circuit may require at least two integrated circuits (ICs) plus other peripheral devices (e.g. a Schottky diode and an inductor) in a peripheral region of the ICs. Accordingly, the number of components in a light sensing LED driving circuit may be relatively large, which may increase costs and size of the light sensing LED driving circuit.